Fuel Xfeed off for landing

[trommel]

I have often been told that, during S/E ops, prior to landing you should turn the fuel xfeed off and return the engines fuel feed to their primary tanks.

Is this because fuel systems are not certifiied for operations at Go around thrust/power with the xfeed operating or

Is it something that has always been best practice since the second world war.

I have been told this when carrying out OCA's in Jets and turboprops none of which specifically prohibit landing with the xfeed on during.

Does anyone know which one it is? as i have been told both.

Thanks